Maximum demand controller and load indicator for electric power installations



C. C. GOW. MAXIMUM DEMAND CONTROLLER AND LOAD INDICATOR FOR ELECTRICPOWER INSTALLATIONS.

APPupanou' FILED NOV, so, 1918 1,31%,471w Patented Aug. 26, 1919.

m 1 a w M N m n I 6 H D, s l O I 2""5' J A: h I Ergmefr C. C. GOW.MAXIMUM DEMAND CGNTROLLER AND LOAD INDICATOR FOR ELECTRIC POWERINSTALLATIONS.

AIFLICM'ION FILED NOV. 30. I918.

9 r w m 6Q M Wig 2W n m 1 C. C. 60W. 7 MAXIMUM DEMAND CONTROLLER ANDLOAD INDICATOR .FOR ELECTRIC POWER-INS TALLATIONS.

APPLICATION FILED NOV. 30 I9I8.

Patented Aug. 26, 1919.

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I MAXIMUM DEMAND CONTROLLER AND LOAD LNDIQA TOR FOR ELECTRIC POWERINSTALLATIONS. APPLICATlON FILE'D'NOV. 1918.

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.interval of time, which may be,

perhaps fluctuates rapidly,

UNITED strains- T NT orrion.

COLIN C. GOW, OF LONDON, ENGLAND.

MAXIMUM-DEMAND CONTROLLER AND LOAD-INDICATOR non minerals-rowanINSTALLATIONS. r

. Specificatin of wa Patent.

Patented Aug. 26, 1919.

Application filed November .30, 1918. Serial No. 264,856.

g To all whom it may concern:

Be it known that I, CO INCLARENOE' Grow, King of Great Britain, resldasubject of the ing in London, England, have invented certainnew anduseful Improvements in Maximum-Demand Controllers and Load-Indica whichthe following is a specification.

In industrialinstallations using electric energy it is often importantthat the average demand for power during a given interval of time shouldnot exceed a fixed maximum value. If this maximum demand during thegiven interval is exceeded at any time, on the onehand'the safety of theworking plant may be endangered, and on the other hand considerableneedless expense maybe incurred if the installation is supplied withpower from a central station and the charge depends, as it usually does,not only on the energy used but also on-the maximumde= mand for. power(averaged over an agreed for example, half an hour) during the currentterm.

It is obvious that the most efficient and most economical working of theinstallation occurs when the load factor is unity and when the powerdemand always approxi-' mates to but never exceeds the maximumpermissible value. If, on the other hand, the average load during thegiven interval on any one occasion largely exceeds that at any othertime, the loss may be very serious. In electrically operatedindustriesin which the power varies considerably and it is impossible to maintainthe average demand at the required values by'observation or anindicating or recording w-attmeter.

According to the present invention, an instrument'is provided foroperating an electrical plant which the energy is being consumed at anytime that rate is more or less than a predetermined value, and in theformer case gives a warning by abell, or other suitable means, towardthe close of the given v interval of time, and if the warning is nottape I a given quantity of energy,

shows the rate at-which compared withthe amount for measured hasexpired, '5. 6., until the instrument is re-set.

According to the invention. also the in-' strument is automaticallyre-set at the end of every time interval whether the load is on or oflfbut, apart from this re-setting action, the current supply to theinstrument is cut off whenever the load is taken off.

Thetime intervals at'which the instrument is re-set must synchronizewith the timeintervals determined by the timing devlce of the powercompany supplying the electric energy.

In a construction according to the invention,two tapes or cords ofsuitable flexibility are wound intermittently at frequent intervals oftime on to drums side by side; the one tape is actuated a clock so thatits motion is at a constant rate, and the other by an ergmeter, whichmoves the tape through 'a constant distance whenever a given amount ofenergy has been'expended.

A convenient method of insuring that the actuated by the ergmeter movesthrough the same distance at each advance I consists in anelectromagneticdevice, by

which a plunger is actuated througha constant distance whenever by theergmeter, this distance, however, be-

ing capable of regulation. For this purthe coil is energized pose, asthe plunger is moved in one direction the drum actuating the powerrecord:

ing tape is advanced byja clutch device through a distance correspondingto the stroke of the plunger. 0f the stop the tape will advance by thesame amount whenever the ergmeter has recorded but the value of thisconstant advance can be varied as required according to the load atwhich it is desired to maintain the working plant. The time-operatedtape is actuated by asirnilar device.- The relative advance of the twotapes shows at any moment the actual consumption of energy during theinterval as which the instrument has been set.

The drums upon which the tapes are wound are automatically reset whenthe time-operated tape has completed a given advance, that 1s, at theend of the given time For a given setting 'H, when energized,

advance too rapidly and reach a certain point prior to the resettingaction, a bell or other signal is operated and, when the ergmeteractuated tape has further advanced to a position corresponding to themaximum average demand set, a trip coil is energized which automaticallycuts off the supply of energy,

In the accompanying drawings Figure 1 shows diagrammatically the generalarrangement of the circuits and actuating apparatus of an instrumentaccording to the invention. Fig. 2 is a front elevation of an example ofan instrument according to the invention. Figs. 3 and 4 are respectivelya back and side elevation of the instrument.

Referring to Fig. 1, A is a coil connected with leads 1 and 20f a lowtensionsingle or polyphase alternating current'supply and is energizedso long as those leads are live. The coil A, when energized, closes aswitch a Which connects leads 3 and 4 with a'direet current source ofsupply; from theleads 3 and 4: circuits are taken to the various partsof the apparatus. A relay coil B is inserted in a circuit branched fromthe leads 3 and 1 over conductors 5 and 6 and is energized from a clockovera contact 8 at regular intervals of time, for example every halfminute. Relay B, when energized, closes its contact 6 and therebyenergizes over leads 6 and 7 an electromagnet C which rotates a windingdrum carrying a vertical tape through a given angular step at eachcontact. 3

D is arelay connected with the leads 3 and at, over leads 5 and 9, whichis energized over a contact 10 whenever the integrating wattmeterrecords the consumption of a predetermined unit of electric energy.Relay by closing its contact a, energizes over leads 9 and 11 anelectromagnet E which rotates a winding drum carrying a vertical tapethrough a given angular step at each contact. The tapes operated by thetwo drums are ranged side by side and carry indices which are easilyseen by the workmen operating the power units of the installation.

F is an electromagnet resetting the winding drums energized over leads 5and 13 when a contact 12 is closed by the clock. This contact is closedat the expiration of each interval of time over which the averagemaximum demand is integrated.

If during this time-interval the tape operated by the power drumhasreached nearly to the upper limit of its travel, contacts 14 and 15are closed which cause a warning bell G to ring, or some other suitablesignal to be operated. At the end of the trai'el of the power-driventape contacts 15 and 16 are closed which energizes a relay H. The relaycloses over leads 1'? and 18 the circuit of a trip coil K, which inknown manner opens the switch K and cuts lower end of which is a minedunit of energy ofl'lthe supply of power and renders the leads 1 and '2dead.

Similar parts are denoted by the same reference characters in Figs. 2 las in Fig.1.

When the magnet E is energized by the, action of relay D its armatures cand 6 are attracted t0,,the iron core 6. The armature 6 is secured to abent lever 17 pivoted at 18; the lever 17 is connected by a link 19 atthe pin 19 in contact with a brake lever 20which is pivoted at 21 andcarries at one end a brake 22 normally held by a spring 23 against therim of a drum L on which a ta e M is wound.

When the armature 1' is attracted it rotates the bent lever 17 so as toremove the brake from the winding drum L the armature 6 which is adaptedto move with a momentary de'lay behind the armature 6 is connected by astirrup piece 24 with a lever 25 pivoted at 26. The free end of thelever carries a clutch 27 engaging with the drum L and in contact withthe upper sur face of the free end of the lever 25 is a plunger rod 28of a plunger 29 sliding in a vertical cylinder 30. The plunger and rodare raised whenever the armature 6 is attracted to the core 6 of themagnet E until the plunger 29- meets the end of the cylinder 30; theposition of the cylinder, and with it the length of the stroke of theplunger, can be adjusted by the milled head 32.

For the same setting of the screw the stroke of the plunger and theangular rota-- tion of the drum L is constant at every attraction of thearmature 0 which occurs whenever the switch 10 is closed by theintegrating wattmeter whenever a predeterhas been supplied to screw 31operated by the the installation.

On the release of the armature (Z of the relay D, magn'etE isdeenergized and the armature c and the plunger 29 fall by gravity andreturn the lever 25 and with it the clutch 27 to its normal position ,inwhich it is supported by an arm 33 of an angular lever 3334.

The lever 33, 34 is connected by a link 35 with a lever 36 pivoted onthe hinge 21 and operated by the armature 6 The connection between theclutch 27 and the arm 33 of the angular lever 33, 34 is such that whenthe armature c is attracted the clutch is forced into engagement withthe drum L and when the armature is released the clutch is disengaged.

The movements of the plunger 29 are damped by the time required for theair be tween the plunger and the head of the cylinder 30 to pass througha small hole 37 pro vided in the cylinder head.

The eleetromagnet F is energized as described above when the switch 12is closed energized closes the switch h and 'as-ex-v plained above,completes'the circuit ofthe said intervals.

by the clock at the expiration of each interval of time ovenwhich themaximum de mand is to be integrated and attracts its armature f and by apin 38 on the armature coiiper-ating with the brake lever 20 releasesthe brake 22 and allows the drum L to return to its normal settingagainst a stop 39 on the action of a weight m carried by the tape M.-The weight m is guided vertically on rods 40. To the weight m aspringcontact m, (Fig. l) is secured adapted to connect the contacts 14and 15 and ring-the bell G when the tape has traversed acertain;distance and also to connect contacts 15 and 16 which complete thecircuit of the relay-H when the full permissible travel of the tape Mhas been completed. The relay H when trip coil K which maybe suitablymounted to mechanically trip the main supply switch,

rendering leads 1' and 2 dead. Switch (1 then opens and prevents anyfurther action of the irnsti umcnt excepting the operation of there-settmg magnet p The electromagnet C (Fig. 3) is energized over thecontacts of the armature b. of the relayB when the switch 8 is closed bythe." clock. The arm'atures c 0 are arranged. similarly to thearinatures e c of the magnet B and the operations. of clutching, brakingand re-setting the winding drum L are similar to those'described abovein connection with the drum l The tapeN is'loadediwith a weight n andthe relative positions of indices attached to .the. weights m and 71,show at any time whether energy is being supplied to the in stallationat a rate corresponding to below or above them-aximum average demandduring the-prescribed interval of time.

Having thus described the natureof the said invention and the best meansI know-of carrying the same into practical effect, I

claim 1. A maximum demand controller and loadindicator for an electricpower insta'llation comprising,in combination, a clock, an ergmeter, andtwo indicators, one operated by the clock at a constant rate, and theother by .the ergmeter at a rate proportional t sthe energy supplied tothe installation throughout the given time interval over which themaximum demand is, averaged, and meansfor automatically re-setting the,indicatorsat'the terminationof each of the 2. A maximum demandcontroller and load indicatorfor an electri'c' power installationcomprising in combinationtwo adja-' cently disposed drums and flexiblemembers wound respectively on said drums, a clock and an ergmeter, oneof the said drums being actuated intermittently by ,the clock at aconstant rate and the other drum being actuated by the ergmeter througha constant angular distance whenever a given amount a of energy, asmeasured by the ergmeter, has

been supplied to the installation.

3. A maximum demand controller and load indicator for an electric powerinstallation, comprising in combination two adjacently disposed drumsand bands wound respec'ively onsaid drums, a clock and an ergmeter, oneof the said drums being'actu-ated intermittently by the clock at aconstant rate ble amounts at each energization of the saidelectromagnetic device,a clock and an ergmeter, one of the said devicesbeing energized whenever a given amount of energy has been supplied tothe ergmeter and the other of the said devices being energized atconstant time intervals.

- 5. 1h maximum demand controller and loadindicator for an electricpower i'nstal-f lation', comprising in combinationiwo drums and flexible-members wound respectively on said drums, electromagnetic devices andarmatures operated thereby, brakes and clutches for said drums connectedto said armatures, cylinders, plung'ers operating in said cylinders andconnected to said armatures, the stroke of the plungers. determining theamount of angular advance of the drums when said electromagnetic devicesare energized and flexible members wound on said drum and adapted bytheir relative which energy is being supplied to the installation ismore or less than apredetermined value.

6. A maximum demand controller and loadindicatorfor an electric powerinstallation, comprising in combination two drums and flexible memberswound respectively on said-drums, electromagnetic devices and .armaturesoperated thereby, brakes and clutches for said'drums connected to saidarmatures, cylinders adjustable in the direction. of their axes,plungers operating in said cylinders and connected to said armatures,the stroke of the plungers ,bein controlled by the axial position of thecylinders and determining the amount of angular advance" of the drumswhen said electromagnetic demovement to indicate whether 'the rate atbeen supplied to the .flexible member wound vices are energized andflexible members wound on said drum and adapted by their relativemovement to indicate whether the rate at which energy is being suppliedto the installation is determined value.

7. A maximum demand controller and load indicator for an electric powerinstal-v lation comprising in combination a source of direct currentelectricity and a circuit connected" thereto, a clock and a switch inthe said circuit closed at regular intervals of time by the clock, arelay energized when said switch is closed, an electromagnet energizedby said relay, a rotatable drum, a

on the drum and advanced through a given distance when saidelectromagnet is energized, an ergmeter, and

a second switch in a circuit connected to the direct current source andclosed when a predetermined amount of electric energy has said ergmeter,a relay energized when the last mentioned switch is closed and adaptedto close the circuit of a more or less than a pregized when the saidswitch I a second electromagnet, and a second rotatable 3 drum andflexible member advanced through a given distance when said secondelectromagnet is energized.

8. A maximum demand controller and load indicator for an electric powerinstallationcomprising in combination a source of direct currentelectricity, a clock and an ergmeter and circuits respectivelyconnecting the clock and ergmeter with the said source, switches in thesaid circuits, relays energized when said switches are closed, meansoperated by the relays for rotating drums carrying flexible members, aswitch closed by the clock at the termination of each interval of timeduring which the average demand is averaged and a relay enerisclosed andadapted to re-set the drums to their original angular positions.

"In testimony whereof I have signed my name to this specification.

COLIN c. cow.

